The present invention relates to utility trailers and more particularly to utility trailers having a frame capable of being lowered to ground level.
In the prior art, there are several devices used for the lowering or raising of a trailer frame.
For example, one prior art device combines a double tongue arrangement whereby one of the tongues is pivoted in relation to the other by use of a winch and cable. The winch and cable is also used to simultaneously raise and lower the rear part of the frame to provide a substantially parallel relationship with the ground to avoid tilting of a boat or other object being carried by the trailer. The implementation of the rear wheel suspension requires a very complex system of linkages and crank arms at the axle to allow the trailer frame to be raised or lowered. Another prior art device employs independent suspension of each of the rear wheels without having an interconnecting axle. This device is subject to distortion of the frame due to the lack of an axle to keep the wheels in proper alignment. Further the front portion of the tr iler is not adapted to be lowered.
In summary, prior art devices for lowering the frame of a trailer to approximately ground level are generally subject to one or more of the following disadvantages:
A. Complex crank and arm mechanism attached to wheel suspension;
B. Lowering only the rear of the trailer, thus resulting an incline of the trailer;
C. Complex cam arrangement for raising or lowering the trailer frame;
D. Independent wheel suspension which reduces the rigidity of the trailer and created alignment difficulties.